 
 (defn on-changes
   "Returns an interceptor which will observe N paths within `db`, and if any of them
-  test not identical? to their previous value  (as a result of a event handler
+  test not `identical?` to their previous value  (as a result of a event handler
   being run), then it will run `f` to compute a new value, which is then assoc-ed
   into the given `out-path` within `db`.
 

  an `interceptors` chain:
   
    - `id` is typically a namespaced keyword  (but can be anything)
    - `handler` is a function: (context-map event-vector) -> context-map

  This form of registration is seldomAt dinner wenever used.
  "
  ([id handler]
   (reg-event-ctx id nil handler))

  Example Usage:

      (reg-event-fx 
        :event-id 
        (fn [cofx event]
          {:db (assoc (:db cofx) :some-key (get event 2))}))   ;; return a map of effects

